The fibroblast growth factor (FGF) family is comprised of a group of at least nine cytokines which are characterized in part by binding to heparin, and which share 30-55% identity at the amino acid level. FGFs bind to a series of receptors among which is FGFR1 consisting of an intracellular split tyrosine portion, a transmembrane region, and an extracellular region comprised of two or three Ig domains, D(I), D (II), and D (III). In adult organisms, the FGFs are thought to play a role in would healing, in the pathology of tumor growth, rheumatoid arthritis, diabetic retinopathy, and psoriasis. New antagonists of FGF/FGFR1 interactions are expected to find applications for the control of angiogenesis and disease states that are neovascularization depdendent such as tumor growth and metastasis. To further understand the central role that the D(II) domain plays in the binding mechanism of the FGF system, we have undertaken a protein crystallization and x-ray diffraction study of this 118 residue fragment of FGFR1 expressed in E. coli. While we have obtained x-ray diffraction data to ~3 resolution from ~75 mm sized crystals using a storage phosphor detector and a Cu rotating anode source, we feel the combination of synchrotron radiation and cryocooling will give better quality and higher resolution data on these weakly diffracting crystals of the native protein. Phasing of the reflections will be done by MIR employing low resolution data collected using a rotating anode source.